This invention relates to flashing. In particular it relates to membrane flashing which is flashing used against the surfaces of materials such as structural steel beams, steel lintels, or other structural steel elements buried in masonry that need protection from penetrating moisture which can cause corrosion. A common form of protective membrane flashing is "through-wall" flashing which is flashing positioned in the masonry so as to guide moisture back to the exterior surface and thus prevent penetration into the interior of the masonry wall.
Protective membrane flashing or through-wall flashing that have been hitherto described have been generally of three types. One has been an asphaltic type wherein asphalt is coated on both sides of a flexible support such as paper or the like. Another type of material used for through-wall flashing has been corrosion-resistant metal, as for example, copper or stainless steel. A third type is plastic flashing. Each of these flashing materials has certain disadvantages.
Metallic flashing is expensive and typically requires precise preforming by the use of a brake or the like which is difficult where there is much wall unevenness. Also, metallic flashing has a relatively low flexure resistance. Plastic flashing typically has a very low resistance to cutting or puncturing, while asphaltic flashing is notorious for its poor resistance to flexure and unsatisfactory resistance to low temperatures.
The present invention incorporates for the first time all of the desired characteristics and performance for protective membrane flashing. The products of this invention combine the qualities of low cost, high flexure resistance, high cut resistance, high resistance to low temperatures, light weight and compactness with free form flexibility. The products of this invention do not require any preforming when used as flashing, but may be draped by the mason so as to follow the contours and unevennesses in masonry construction. This contrasts with typical construction procedures where the contractor is responsible for the flashing material and must preform the material into the appropriate shape on a brake or similar device and then deliver it in preformed shape to the mason who applies it to the particular lintel, spandrel, sill, coping or the like.
Other objects and advantages of this invention will be apparent from the description and claims which follow.